Insulin resistance is a crucial factor for the development of type 2 diabetes and a major health problem for older adults. It is the principal mechanism by which obesity is considered to increase the risk for type 2 diabetes and is a key feature of the metabolic syndrome. The elevated prevalence of obesity and type 2 diabetes in the older population has important consequences on the morbidity and mortality as well as on the economic burden on society. Controversy currently exists as to whether or not aging contributes to insulin resistance. Many potential factors confound the association between aging and insulin resistance, including obesity and physical inactivity.